During the last 18 hours of larval development, the salivary glands of Drosophila larvae produce six proteins which are used as pupal glue. The structural genes for two of these glue proteins have been mapped. Both correspond to polytene chromosome puffs which are active when the proteins are being synthesized. Recent work has shown that there are two active genes in one of these puffs, 3C11-12, and three in the other puff, 68C. This proposal explores the organization of these sequences further and begins to examine the control of expression of the glue protein genes. Individual glue protein mRNAs will be isolated by hybridization to cloned cDNA sequences which hybridize to the puffs. The individual RNAs will then be translated and the products identified by precipitation with specific antibodies. Deletion mutants will be isolated which remove sequences on one or the other side of the gene which specifies the glue protein P3. Their effect on P3 expression will be determined and the endpoints of the deletions located by hybridization to cloned sequences which include the gene. These experiments will define the region required for gene expression and may identify regulatory sites. Several strains of flies have abnormal expression of P3. To determine which level of gene expression is defective we will measure hybridization of specific cloned sequences to nuclear and cytoplasmic RNA of normal and abnormal strains. We will search for DNA sequence alterations by hybridization of restriction fragments from the abnormal strains to cloned sequences from the normal strain. Sequence changes will be detected by change in size of restriction fragments of digestion of mismatched sequences by nuclease S1. The gene for another protein, P5, will be mapped so that possible regulatory mutants can be studied and compared with those affecting P3. Clones carrying P5 cDNA inserts will be identified by hybridization with RNA from P5+ and P5- strains.